Polyphenyl ether stabilizers



United States Patent 3,151,082 POLYPHENYL ETHER STABEIZERS Wesley L. Archer, Midland, Mich, assignor to The Dow Chemical Company, Midland, Mich, a corporation of Delaware No Drawing. Filed Sept. 5, 1961, Ser. No. 135,723 3 Claims. (Cl. 252-52) The present invention relates to antioxidants and viscosity improvers for polyphenyl ether high-temperature, high-pressure lubricants. More particularly the present invention concerns the use of and polyphenyl ether composition containing phenyl benzoate and/or diphenyl phthalate. These compounds have been tested and found to reduce the degradation of the class of high-temperature, high-pressure lubricants having the general formula wherein n is an integer from 2 to 6 or more. The employment of as little as 0.5% by weight of one of the stabilizer compounds based on the total weight of the total composition, will reduce degradation of the polyphenyl ether lubricants and thus reduce the viscosity increase of the lubricant composition due to such degradation. Good results are achieved when employing from about 0.5 to about 1.5% by weight of one of the stabilizer compounds.

It has been found that the viscosity of the polyphenyl ethers increases when degradation occurs under high-temperature operations. Therefore, the increase in viscosity became a convenient measure of the degree of degradation which occurs in polyphenyl others during high-temperature tests wherein oxygen was introduced to simulate actual operation as a lubricant in various systems. The use of viscosity as a measure of degree of degradation and/ or stabilization resolved itself readily to the mathematical equation for percent improvement of stabilization according to the following equation:

X 100=Percent stabilization V =Percent viscosity increase of unstabilized polyphenyl ether after oxidation treatment V =Percent viscosity increase of stabilized polyphenyl ether after oxidation treatment The term percent stabilization is used hereinafter to have the meaning above assigned and is calculated as above set forth. ,7

The following examples illustrate the present invention but are not to be construed as limiting.

Example 1 A 50 g. sample of bis(phenoxyphenyl)ether containing 1% by weight of phenyl benzoate (heated on a steam 3,151,082 Patented Sept. 29, 1964 "Ice Example 2 In a manner similar to that employed in Example 1, employing 1.0% by weight of diphenyl phthalate in place of phenyl benzoate, the percent stabilization was found to be 72.

I claim:

1. A high-pressure, high-temperature lubricant com-- position consisting essentially of a polyphenyl ether havteas wherein n represents an integer from 2 to 6, and, as the essential antioxidant and viscosity improver, an effective amount of a compound selected from the group consisting of phenyl benzoate, diphenyl phthalate and mixtures thereof. 7

2. A high-pressure, high-temperature lubricant composition consisting essentially of a polyphenyl ether havinlet) wherein n represents an integer from 2 to 6, and from 0.5 to 1.5% by weight, based on the total composition, of phenylbenzoate.

3. A high-pressure, high-temperature lubricant composition consisting essentially'of a polyphenyl ether having the formula itlit] wherein n represents an integer from 2 to 6, and from 0.5 to about 1.5% by weight, based on the total composition, of diphenyl phthalate.

References (Zited in the file of this patent UNITED STATES PATENTS 2,215,590 Maverick Sept. 24, 1940 2,231,248 Bowden Feb. 11, 1941 2,347,217 Prutton et al. Apr. 25, 1944 2,940,929 Diamond June 14, 1960 

1. A HIGH-PRESSURE, HIGH-TEMPERATURE LUBRICANT COMPOSITION CONSISTING ESSENTIALLY OF A POLYPHENYL ETHER HAVING THE FORMULA 